On Monday, August 14, 2017 at 4:25:50 PM UTC-4, Bob wrote:
Can I plug the base-unit into the phone-jack and use its cordless handset in a different room?

Yes. One thing you might want to check though is how you check for
and pick up messages. I've always used the main base station to listen to them
on the speakerphone. You may be able to retrieve them from the
other handsets too, seems logical, but I'd check the features/
instructions for whatever you decide to buy. Probably a lot of
choices on Ebay too.


Can I can buy only a charger for that cordless handset?

Probably, but the typical gear is sold as a set of about 4 phones
with chargers. Costco for example always has several or more
choices for ~$45.